Fantastical by Flexibits has been updated to version 1.2.2 to address, among other things, Gatekeeper support in Apple's forthcoming Mountain Lion.
Fantastical is a fantastic tool for the Mac that I've been using for quite a while (here's our comparison of Fantastical and Today). It lives unobtrusively in your Menu Bar and offers fast, natural language creation of calendar events. You can also use it to edit existing appointments, browse what you've got scheduled and sync with iCal, BusyCal, E
